Engines may use a turbocharger to increase engine torque/power output density. In one example, a turbocharger may include a compressor and a turbine connected by a drive shaft, where the turbine is coupled to the exhaust manifold side and the compressor is coupled to the intake manifold side. In this way, the exhaust-driven turbine supplies energy to the compressor to increase the pressure in the intake manifold (e.g. boost, or boost pressure) and to increase the flow of air into the engine. The boost may be controlled by adjusting the amount of gas reaching the turbine, such as with a wastegate.
However, when matching a turbocharger to an engine, there is a constant trade-off between low end torque capability limits from surge, and high end performance limited by flow losses and turbine sizing. In order to address these issues, devices such as Inlet Guide Vanes (IGV), compressor housing grooves, and casing treatments can be implemented into the turbocharger design. However, the inventors herein have recognized that such devices may adversely affect the high end performance flow losses since such approaches are intrusive into the flow field or boundary layer, and may lead to limits on the high end compressor flow capacity, reduced peak performance capabilities of the engine, and Noise Vibration and Harshness (NVH) issues. Further, the inventors herein have recognized that attempts to improve the high end flow capacity of a compressor via adjusting wheel diameter, aspect ratio, and Air/Radius (A/R) ratio may also adversely affect the low end performance capability and transient response of the engine.
As one example, the above issues may be addressed by a method for controlling a compressor inlet flow of an engine turbocharger system comprising: directing air from a high pressure source to an inlet upstream of a compressor wheel via a conduit coupled to the inlet and the high pressure source, where the conduit is obliquely coupled to the inlet.
In this way, the compressor inlet velocity flow field can be tailored and controlled to increase the efficiency of the compressor rotor, increasing the surge margin of the compressor, reducing low end NVH effects such as tip-in and tip-out whoosh, improving transient response characteristics such as time-to-torque, and minimizing the high end flow loss effects associated intrusive devices, for example.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.